Rocking electric furnace ventilating system



Jan. 6, 1942. J R ALLAN 2,2es,9s

ROCKING ELECTRIC FURNACE VENTILATING SYSTEM Filed Aug. 30, 1939 3Sheets-Sheet 1 Fiz/ I l I Jams E ALLAN FPANXH AMos [/vue/vra es u!TTOENE V* hm J. R. ALLAN nm; 2 9

ROCKING ELECTRIC FURNACE VENTILATING SYSTEM Filed Aug. 30, 1939 3Sheets-Sheet 2 JAMES'R ALLAN FRANKH AMOJ vi rrenave-w J 9 J. R. ALLANETAL 9 ROCKING ELECTRIC FURNACE VENTILATING SYSTEM Filed 1939 -3Sheets-Sheet 3 I i 2 I 5 1 nm L Uni L sa W x I H 7- i a 'L 6 u .6 a 6 iHI* m, FI-,9.6 3 H m /ZMES E.ALLAN FRANK h'. AMos NVENTOQS Patented Jan.6, 1942 BOCKING ELECTRIC FURNACE VENTILAT- ING SYSTEM James R. Allan,Oak Park, and Frank H. Amos.

Fox Lake, Ill., asslgnors to American Air Filter Company, Inc.,Louisvilie, Ky., a corporation of Delaware Application August 30, 1939,Serial No. 292,(594

1 Claim.

This invention relates to improvements in ventilating systems forelectric melting furnaces. While the invention is applicable to rockingelectric melting furnaces generally, it is particularly suited forapplication to, and hereinafter explained in connection with, anelectrlc furnace of the type which is rocked 'or tilted about a fixedaxis during the pouring operation.

Heretofore, tilting furnaces in metallurgicai foundries and the likehave been ventilated, to remove the iumes, gases and dust escaping fromthem during operation, by the use of large propeller-type fans usuallylocated in the roof of the foundry or other building which houses theiurnace. With this type of installation, it is ordinarily necessary tomove from 75,000 to 250,000 C. F. M. of air from the building in orderto pro `duce a moderately eflective ventilating' draft around thefumace. Even then, the ventilating results are not very satisfactory,while the removal of such enormous quantities of air neces- 'sarilybrings about high-heating costs during cold weather. Nevertheless, thismethod has been extensively used because of the difiiculty ofeil'ectively housing and continuously ventilating the furnace without,at the same time, interfering with the loading, pouring'and otheroperations ot the furnace.

The principal object of the present invention is to provide a simpleexhaust hood for effectively housing and continuously ventilating thei'umace without interfering with its operation.

Another important object is to render furnace ventilation eflicient andeffective while reducing the flow of ventilating air to a fraction ofthat heretofore required. v

The invention is illustrated in the accompanying drawings, wherein:

Figs; 1 and 2 are side elevations ot an embodiment of the invention asapplied to a conventional electric melting furnace in normal and tiltedpositions respectively, the furnace being shown in solid lines and theembodiment in dotted lines;

Fig. 3 is a top plan view of the arrangement shown in Flg. 1 with theembodiment in solid lines and the furnace in dotted lines, a portion ofthe furnace parts being omitted for the sake oi cleamess;

Figure 4 is a. front elevation of the structure shown in Figure 3;

Figure 5 is a side elevation taken from the right of Figure 4; I y

Figure 6 is a section taken along line 5-5 of Figure 5;

Figur-e 7 is a section taken along line 1-1 of Figure 6; and

Figures 8 and 9 are sections taken along lines 8-8 and 9-9,respectively, of Figure 3.

The invention is illustrated as applied to a conventional electricfurnace F having circular bottom and top walls separated by acylindrical member providing the side walls. The cylinder is provided,at opposite sides, with diametrically opposed charging doors D and, atits front, with a pouring spout s while the top wall contains suitableopenings to receive the electrodes E.

Generally stated, the invention consists in 'mounting, on the top of thefurnace for movement with it, an exhaust hood, having a suction canopyor awning over each door and spout, and connecting the hood to anexhaust system through a flexible connection which accommodates thetilting movement of the furnace without interrupting the flow ofventilating air. Accordingly, an exhaust hood i, composed of sheet metalin the form of a wide shallow cup, is in- ,verted over and mounted uponthe top of the fumace F to provide a top air chamber thereover. The topof the hood l is provided with openings through which the electrodes Epass. The annular clearance space between each electrode and theperiphery of the opening through which it passes provides an inletthrough which outside air may be drawn along the electrode into the hoodto prevent the escape of furnace fumes and gases from that area of thehood. These openings preierably are formed in a plate 2 composed of asuitable non-magnetic material such as nickel-chromium alloy. The platemay be welded or otherwise Secured to the hood l.

The sides of the hood l are cut away to form openings directly over thedoors D and spout S.

. At these openings, the hood is outwardly extended by suction canopies3 which depend downwardly approximately to the level of the upper end ofthe door and spout openings. These canopies, which form air passageways'leading from the door and spout areas into the top air chamber, aredimensioned to accommodate such flow of air as may be required to carryoff the gas fumes and dust escaping through the furnace openings.

provided with a slot 4 to accommodate the furnace-door Operating leversL.

The hood also is provided with an outlet manifold 5 preferably locatedbetween the spout canopy and one of the door canopies. The manifold 5isconnected to the stationary duct S of an exhaust system through a.fiexible form of connection capable of accommodating the tiltingmovement of the furnace without interrupting the flow of air. While thismay be accomplished in various ways, as through the use of a fiexiblepipe, it preferably is accomplished by aligning the furnace end of the-duct 6 axially with the tilting axis A of the furnace and connectingthe manifold 5 directly to the duct 6 through an interposed elbow 'Iwhich is rotatably mounted in the duct 6. The duct 6 and elbow 'Lmay berotatably held together in any suitable ni'nner as by the axial bolt 8.With this form of connection, the elbow 1 swings about the same centeras the furnace, when the latter is moved between its normal and tiltedpositions, and thus maintains open communication between the hood andthe exhaust system at all times. In many installations, it is 'notpossible to place the duct 6 in a'xial alignmentwith the axis A due tothe location of building supports or other fixed abut-` g used toventilate electric urnaces which are may be telescopically fitted to thedepending sleeve 5a of the outlet manifold 5.

With a system of this character, it is only necessary to moveapproximately 4,000 C. F. M. of air per ton of furnace Capacity. I Witha flow of this magnitude and with air-inlet openings designed toaccommodate such flow at a velocity of approximately 500 lineal feet perminute, substantially all of the gases, fumes and dust, escapingthefurnace openings, will be drawn directly into the exhaust hood andthus efiectively prevented from drifting into the atmosphere of thebuilding in which the furnace is housed. The exhaust hood does notinterfere with the chargmounted on a rocker for rocking or tiltlngmovement between normal and pouring positions. This type of fumace doesnot, of course, have a fixed axis, corresponding to axis A, with whichthe duct S can be aligned. The same type of connection between duct andhood, as previously described, can, however, be readily used, particu-'larly when the duct is located adjacent the contaict area about .whichthe fumace rocks. i. e.. the area along which the rocker engages thebase member during the rocking movement. In such installations, the ductpreferably is located below the level of the contact area.

Having described our invention, we claim:

A ventilating system for an electric melting furnace, having a spoutopening, one or more other "charge'f openings, through which fumac gasesand dust escape to the outer atmosphere during operation, and a fixedfurnace tilting axis below the level of said spout opening but more orless adjacent thereto, comprising: an exhaust hood extending over thetop of the furnace and mounted thereon for movement therewith; said hoodhaving a suctioncanopy--extending over and in open communication withthe outer atmosphere adjacent the spout opening andeach of the othercharge openings to draw the escaping gases and dust into said hood-andan outlet manifold terminating in a depending sleeve; an exhaust systemhaving a duct termnating near the furnace in substantially axialalignment with said fixed axs; and an elbow-pipe connection between saiddepending sleeve and duct. said pipe connection being telescopicallyfitted to the sleeve and' rotatably mounted on the duct.

JAMES R. AILAN. V FRANK H. AMOS.

